Racism, masculine peer-group relations and the schooling of African/Caribbean infant boys

The past decade has witnessed the publication of a growing number of important ethnographic studies investigating the schooling experiences of Black students. Their focus has largely been upon student-teacher relations during the students' last few years of compulsory schooling. What they have highlighted is the complexity of racism and the varied nature of Black students' experiences of schooling. Drawing upon data from a year-long ethnographic study of an inner-city, multi-ethnic primary school, this paper aims to compliment these studies in two ways. Firstly the paper will broaden the focus to examine how student peer-group relations play an integral role, within the context of student-teacher relations, in shaping many Black students' schooling experiences. By focussing on African/Caribbean infant boys, it will be shown how student-teacher relations on the one hand, and peer-group relations on the other, form a continuous feed-back loop; the products of each tending to exacerbate and inflate the other. Secondly, by concentrating on infant children, the paper will assess the extent to which these resultant processes and practices are also evident for Black pupils at the beginning of their school careers - at the ages of five and six.

Cloning and characterization of the Burkholderia vietnamiensis norM gene encoding a multi-drug efflux protein

Polymyxin B-sensitive mutants in Burkholderia vietnamiensis (Burkholderia cepacia genomovar V) were generated with a mini-Tn5 encoding tetracycline resistance. One of the transposon mutants had an insertion in the norM gene encoding a multi-drug efflux protein. Expression of B. vietnamiensis norM in an Escherichia coli acrAB deletion mutant complemented its norfloxacin hypersensitivity, indicating that the protein functions in drug efflux. However, no effect on antibiotic sensitivity other than sensitivity to polymyxin B was observed in the B. vietnamiensis norM mutant. We demonstrate that increased polymyxin sensitivity in B. vietnamiensis was associated with the presence of tetracycline in the growth medium, a phenotype that was partially suppressed by expression of the norM gene.

Genetic analysis of the O-specific lipopolysaccharide biosynthesis region (rfb) of Escherichia coli K-12 W3110:identification of genes that confer group 6 specificity to Shigella flexneri serotypes Y and 4a

We recently reported a novel genetic locus located in the sbcB-his region of the chromosomal map of Escherichia coli K-12 which directs the expression of group 6-positive phenotype in Shigella flexneri lipopolysaccharide, presumably due to the transfer of O-acetyl groups onto rhamnose residues of the S. flexneri O-specific polysaccharide (Z. Yao, H. Liu, and M. A. Valvano, J. Bacteriol. 174:7500-7508, 1992). In this study, we identified the genetic region encoding group 6 specificity as part of the rfb gene cluster of E. coli K-12 strain W3110 and established the DNA sequence of most of this cluster. The rfbBDACX block of genes, located in the upstream region of the rfb cluster, was found to be strongly conserved in comparison with the corresponding region in Shigella dysenteriae type 1 and Salmonella enterica. Six other genes, four of which were shown to be essential for the expression of group 6 reactivity in S. flexneri serotypes Y and 4a, were identified downstream of rfbX. One of the remaining two genes showed similarities with rfc (O-antigen polymerase) of S. enterica serovar typhimurium, whereas the other, located in the downstream end of the cluster next to gnd (gluconate-6-phosphate dehydrogenase), had an IS5 insertion. Recently, it has been reported that the IS5 insertion mutation (rfb-50) can be complemented, resulting in the formation of O16-specific polysaccharide by E. coli K-12 (D. Liu and P. R. Reeves, Microbiology 140:49-57, 1994). We present immunochemical evidence suggesting that S. flexneri rfb genes also complement the rfb-50 mutation; in the presence of rfb genes of E. coli K-12, S. flexneri isolates express O16-specific polysaccharide which is also acetylated in its rhamnose residues, thereby eliciting group 6 specificity.

Strategic development in exact calculation: Group and individual differences in four achievement subtypes

This longitudinal study sought to identify developmental changes
in strategy use between 5 and 7 years of age when solving exact
calculation problems. Four mathematics and reading achievement
subtypes were examined at four time points. Five strategies were
considered: finger counting, verbal counting, delayed retrieval,
automatic retrieval, and derived fact retrieval. Results provided
unique insights into children’s strategic development in exact calculation
at this early stage. Group analysis revealed relationships
between mathematical and/or reading difficulties and strategy
choice, shift, and adaptiveness. Use of derived fact retrieval by
7 years of age distinguished children with mathematical difficulties
from other achievement subtypes. Analysis of individual differences
revealed marked heterogeneity within all subtypes,
suggesting (inter alia) no marked qualitative distinction between
our two mathematical difficulty subtypes.

Animal group forces resulting from predator avoidance and competition minimization

A new model to explain animal spacing, based on a trade-off between foraging efficiency and predation risk, is derived from biological principles. The model is able to explain not only the general tendency for animal groups to form, but some of the attributes of real groups. These include the independence of mean animal spacing from group population, the observed variation of animal spacing with resource availability and also with the probability of predation, and the decline in group stability with group size. The appearance of "neutral zones" within which animals are not motivated to adjust their relative positions is also explained. The model assumes that animals try to minimize a cost potential combining the loss of intake rate due to foraging interference and the risk from exposure to predators. The cost potential describes a hypothetical field giving rise to apparent attractive and repulsive forces between animals. Biologically based functions are given for the decline in interference cost and increase in the cost of predation risk with increasing animal separation. Predation risk is calculated from the probabilities of predator attack and predator detection as they vary with distance. Using example functions for these probabilities and foraging interference, we calculate the minimum cost potential for regular lattice arrangements of animals before generalizing to finite-sized groups and random arrangements of animals, showing optimal geometries in each case and describing how potentials vary with animal spacing. (C) 1999 Academic Press.</p>

Health Awareness Drama by the Mavumbo Youth Group, Mongu Western Zambia, the Trickle Out Project

Video from fieldwork research in Zambia

Low prevalence of primary biliary cirrhosis in Victoria, Australia. Melbourne Liver Group

A prevalence study of primary biliary cirrhosis was carried out in the state of Victoria, Australia, by means of a mail survey of specialist physicians and a review of hospital records. Eighty four cases were identified, giving a prevalence of 19.1 per million population (95% confidence limits (CI) 15.3, 23.7), which is among the lowest in published reports. The prevalence in the Australian born, at risk population (women over the age of 24) was 51 per million (95% CI 37.5, 67.9). Both these figures are considerably lower than those in populations of similar age distribution in the UK and northern Europe. Since most Victorians are descended from British or European settlers, the low prevalence of primary biliary cirrhosis in this study supports the hypothesis that local environmental factors may be important in the pathogenesis of this disease.

Effect on prescribing of the limited list in a computerised group practice

The prescribing of drugs in the therapeutic classes that are affected by the government's limited list was investigated in a computerised group practice of just over 3,000 patients. Prescribable drugs in categories that are affected by the list were identified for two consecutive six month periods before and one six month period after the introduction of the list. A significant decrease in the prescribing of cough and cold remedies, vitamins, and antacids occurred after the list was introduced, whereas no change occurred in the prescribing of laxatives, benzodiazepines, or analgesics. The prescribing of iron and penicillin increased significantly after the list was introduced, whereas the use of H2 antagonists and non-steroidal anti-inflammatory drugs showed no significant change.

Antioxidants, but not B-group vitamins increase the resistance of low-density lipoprotein to oxidation:a randomized, factorial design, placebo-controlled trial

We have conducted an intervention trial to assess the effects of antioxidants and B-group vitamins on the susceptibility of low-density lipoprotein (LDL) to oxidation. A total of 509 men aged 30-49 from a local workforce were screened for total plasma homocysteine. The 132 selected (homocysteine concentration > or = 8.34 mumol/l) men were randomly assigned, using a factorial design, to one of four groups receiving supplementation with B group vitamins alone (1 mg folic acid, 7.2 mg pyridoxine, 0.02 mg cyanocobalamin), antioxidant vitamins (150 mg ascorbic acid, 67 mg alpha-tocopherol, 9 mg beta-carotene), B vitamins with antioxidant vitamins, or placebo. Intervention was double-blind. A total of 101 men completed the 8-week study. The lag time of LDL isolated ex vivo to oxidation (induced by 2 mumol/l cupric chloride) was increased in the two groups receiving antioxidants whether with (6.88 +/- 1.65 min) or without (8.51 +/- 1.77 min) B-vitamins, compared with placebo (-2.03 +/- 1.50) or B-vitamins alone (-3.34 +/- 1.08) (Mean +/- S.E., P <0.001). Antibodies to malondialdehyde (MDA) modified LDL were also measured, but there were no significant changes in titers of these antibodies in any group of subjects whether receiving antioxidants or not. Contrast analysis showed that there was no interaction between antioxidants and B-group vitamins. This study indicates that while B-group vitamins lower plasma homocysteine they do not have an antioxidant effect. Thus B-group vitamins and antioxidants appear to have separate, independent effects in reducing cardiovascular risk.

Effect of B-group vitamins and antioxidant vitamins on hyperhomocysteinemia:a double-blind, randomized, factorial-design, controlled trial

Mild hyperhomocysteinemia is accepted as a risk factor for premature cardiovascular disease. In a population with a high prevalence of cardiovascular disease, we screened a group of clinically healthy working men aged 30-49 y (n = 509) for plasma homocysteine and 5,10-methylene tetrahydrofolate reductase (MTHFR) genotype status. Those with mildly elevated homocysteine concentrations (> or = 8.34 micromol/L) were selected for intervention. In a randomized, factorial-design, controlled trial we assessed the effects of B-group vitamins and antioxidant vitamin supplementation on homocysteine concentrations. The 132 men were randomly assigned to one of four groups: supplementation with B-group vitamins alone (1 mg folic acid, 7.2 mg pyridoxine, and 0.02 mg cyanocobalamin), antioxidant vitamins alone (150 mg ascorbic acid, 67 mg RRR-alpha-tocopherol, and 9 mg beta-carotene), B-group vitamins with antioxidant vitamins, or placebo. Intervention was double-blind. A total of 101 men completed the 8-wk intervention. When homocysteine concentrations were analyzed by group, significant (P <0.001) decreases (32.0% and 30.0%, respectively) were observed in both groups receiving B-group vitamins either with or without antioxidants. The effect of B-group vitamins alone over 8 wk was a reduction in homocysteine concentrations of 27.9% (95% CI: 22.0%, 33.3%; P <0.001) whereas antioxidants alone produced a nonsignificant increase of 5.1% (95% CI: -2.8%, 13.6%; P = 0.21). There was no evidence of any interaction between the two groups of vitamins. The effect of B-group vitamin supplementation seemed to depend on MTHFR genotype. Supplementation with the B-group vitamins with or without antioxidants reduced homocysteine in the men with mildly elevated concentrations, and hence may be effective in reducing cardiovascular risk.